Introduce -dlint flagwip/T20601

As suggested in #20601, this is a short-hand for enabling the usual
GHC-internal sanity checks one typically leans on when debugging runtime
crashes.

2 files changed, 30 insertions, 0 deletions

diff --git a/compiler/GHC/Driver/Session.hs b/compiler/GHC/Driver/Session.hs
index ce08fa49be..6834893b4b 100644
--- a/compiler/GHC/Driver/Session.hs
+++ b/compiler/GHC/Driver/Session.hs
@@ -2530,6 +2530,8 @@ dynamic_flags_deps = [
         (setDumpFlag Opt_D_dump_hi_diffs)
   , make_ord_flag defGhcFlag "ddump-rtti"
         (setDumpFlag Opt_D_dump_rtti)
+  , make_ord_flag defGhcFlag "dlint"
+        (NoArg enableDLint)
   , make_ord_flag defGhcFlag "dcore-lint"
         (NoArg (setGeneralFlag Opt_DoCoreLinting))
   , make_ord_flag defGhcFlag "dlinear-core-lint"
@@ -3917,6 +3919,22 @@ enableUnusedBinds = mapM_ setWarningFlag unusedBindsFlags
 disableUnusedBinds :: DynP ()
 disableUnusedBinds = mapM_ unSetWarningFlag unusedBindsFlags
 
+-- | Things you get with `-dlint`.
+enableDLint :: DynP ()
+enableDLint = do
+    mapM_ setGeneralFlag dLintFlags
+    addWayDynP WayDebug
+  where
+    dLintFlags :: [GeneralFlag]
+    dLintFlags =
+        [ Opt_DoCoreLinting
+        , Opt_DoStgLinting
+        , Opt_DoCmmLinting
+        , Opt_DoAsmLinting
+        , Opt_CatchNonexhaustiveCases
+        , Opt_LlvmFillUndefWithGarbage
+        ]
+
 enableGlasgowExts :: DynP ()
 enableGlasgowExts = do setGeneralFlag Opt_PrintExplicitForalls
                        mapM_ setExtensionFlag glasgowExtsFlags
diff --git a/docs/users_guide/debugging.rst b/docs/users_guide/debugging.rst
index 50a6c279a4..f0a929df5e 100644
--- a/docs/users_guide/debugging.rst
+++ b/docs/users_guide/debugging.rst
@@ -920,6 +920,18 @@ Checking for consistency
    single: consistency checks
    single: lint
 
+.. ghc-flag:: -dlint
+    :shortdesc: Enable several common internal sanity checkers
+    :type: dynamic
+
+    :implies: -dcore-lint, -dstg-lint, -dcmm-lint, -dasm-lint, -fllvm-fill-undef-with-garbage, -debug
+    :since: 9.4.1
+
+    Turn on various heavy-weight intra-pass sanity-checking measures within GHC
+    and its runtime system.  Notably, this does not include
+    :ghc-flag:`-falignment-sanitisation` as it incurs a rather hefty runtime
+    cost.
+
 .. ghc-flag:: -dcore-lint
     :shortdesc: Turn on internal sanity checking
     :type: dynamic